1. Field of the Invention
The present invention relates to a pressing die for use in bonding a covering member to a preformed foam padding (or foam cushion member) in order to produce a vehicle seat. In particular, the invention is directed to a die for pressingly bonding to a covering member the outer surfaces of a foam padding of a one-side-opened type having a hollow therein, for the seat assemblage.
2. Description of Prior Art
FIG. 1 shows a typical one-side-opened and hollow type of foam padding (A) (or foam cushion member) which forms one constituent element for a seat back of a vehicle seat to be produced. This sort of foam padding is preformed, as shown, in a configuration conforming to a desired outer shape of vehicle-seat seat back, which has an opened area (O) defined at its rearward side and an inner hollow areas (X1)(X2)(X3) formed therein.
In general, the foam padding (A) comprises a body portion or frontal wall portion (10) corresponding to a frontal surface of vehicle seat on which a passenger's back rests, four lateral wall portions (12a)(12b)(12c) (12d) extending rearwardly of the frontal wall portion (10), three rearward wall portions (11A)(11B)(11C) extending from their respective lateral wall portions (12a)(12b)(12c)(12d) in a direction inwardly of the padding (A) and generally in parallel with the frontal wall portion (10), terminating substantially in U-shaped edges which define the foregoing opened area (O), and a bendable wall portion (13) projected from the forth or lower lateral wall portion (12d) which faces oppositely towards the first or upper lateral wall portion (12a). All of those portions are preformed integrally together in a predetermined foaming process, using a mold. Thus, as viewed from FIG. 1, it is seen that upper inner area of the padding (A') is surrounded by all the frontal, lateral and rearward wall portions (10, 11A, 11B, 11C, 12A, 12B, . . . ) and thereby provided with an upper hollow area (X1), and that further, a pair of lateral hollow areas (X2)(X3) are defined in both lateral sides of the padding body, respectively, by the corresponding right and left lateral wall portions (12b)(12c) and corresponding right and left rearward wall portions (11B)(11C) in cooperation with the frontal wall portion (10).
Conventionally, in this construction of padding (A), a pair of spaced-apart slits (Y)(Y) are formed by cutting the upper rearward wall portion (11A) in the vertical direction of the padding body, for a purpose to be set forth hereinafter.
FIG. 2 shows a conventional pressure bonding operation, using a conventional plate-like upper pressing die (1A) and a lower die (4) having a working die surface whose shape conforms to that of the frontal surfaces of the foregoing foam padding (A), in order to pressingly bond that padding (A) with two slits (Y)(Y) to a covering member (B) which forms a covering surface of vehicle seat.
The upper pressing die (1A) is fixed to a hydraulic cylinder (5) and may be moved vertically, by operating the cylinder (6), towards and away from the lower die (4). Such pressing die (1A) is formed in a dimensions substantially equal to that of a whole hollow volume which are defined in the padding (A) by the inner back area of the frontal wall portion (10) and the above-stated three hollow areas (X1)(X2)(X3) in aggregation, so that the die (1A) may be fit secured within the padding (A) and the frontal wall portion of the padding (A), on the whole, may be applied a sufficient pressure from the die (1A) and pressed evenly against the lower die (4).
In operation, the .covering member (B) is turned upside down and placed upon the lower die (4). Next, an operator takes up the padding (A) and folds upwardly a part of its upper rearward wall portion (11A) between the two slits (Y)(Y), as indicated by the arrow in FIG. 2, to open the upper hollow area (X1), thereby enlarging the opening (O) lengthwise of the padding (A). Then, the operator can easily let the upper die (1A) inserted into the hollow portions (X1)(X2)(X3) by stretching upwardly other remaining rearward wall portions (11B)(11C). In that way, the padding (A) is secured to the upper die (1A) as shown in FIG. 2. It is noted that the thus-upwardly-folded part of the upper rearward wall portion (11A) between the two slits (Y)(Y) is, of course, naturally returned to the ordinary horizontal plane, as in FIG. 1, in registry with other wall portions (11B)(11C) by virtue of elastic recovery nature of the foam padding (A) per se. Then, a proper adhesive (AD) is applied to the frontal surface (10) of padding (A), and by operation of the cylinder (6), the upper die (A) is lowered towards the lower die (4) as shown in FIG. 2 so that the padding (A) is pressed and bonded to the reverse side of the covering member (B) on the lower die (4). After completion of the pressure boding operation, the upper die (1A) is raised by further operation of the cylinder (6) away from the lower die (4) and the operator again folds upwardly the same part of the upper padding wall portion (11A) to forcingly remove the padding (A) from the upper die (1A).
However, the above-described conventional padding (A) and bonding operation by use of the conventional pressing die (1A) has been found defective in that the two slits (Y)(Y) create undesired irregular or uneven points on the flat plane of corresponding upper rearward wall portion (11A), which results in forming an unpleasant non-uniform point, possibly objectionable creases, on the evenly stretched surface of covering member (B) bonded over the padding (A) and leaving an aesthetically poor problem on the outer appearance of the resultant seat. Furthermore, it is difficult on the part of operator to quickly insert the upper die (1A) into the hollow portions of the padding (1A) because of such troublesome need for folding up the cut area of padding between the two slits (Y)(Y) in question. Moreover, the given plate-like upper die (1A) limits its use to a particular padding having a length of inner hollow portion substantially equal to the length of upper die (1A), hence making it difficult to adapt the die (1A) for use of another different padding having different hollow length, in which case, it is also difficult to precisely position the padding (A) on the upper die (1A) with respect to the lower die (4).